Extract ActionView from Rails

Appraisals

@@ -306,6 +306,7 @@ elsif Gem::Version.new('2.2.0') <= Gem::Version.new(RUBY_VERSION) \
     end
 
     appraise 'contrib' do
+      gem 'actionview'
       gem 'active_model_serializers', '>= 0.10.0'
       gem 'activerecord', '< 5.1.5'
       gem 'aws-sdk'
@@ -451,6 +452,7 @@ elsif Gem::Version.new('2.3.0') <= Gem::Version.new(RUBY_VERSION) \
     end
 
     appraise 'contrib' do
+      gem 'actionview'
       gem 'active_model_serializers', '>= 0.10.0'
       gem 'activerecord', '< 5.1.5'
       gem 'aws-sdk'
@@ -484,6 +486,7 @@ elsif Gem::Version.new('2.3.0') <= Gem::Version.new(RUBY_VERSION) \
 elsif Gem::Version.new('2.4.0') <= Gem::Version.new(RUBY_VERSION)
   if RUBY_PLATFORM != 'java'
     appraise 'contrib' do
+      gem 'actionview'
       gem 'active_model_serializers', '>= 0.10.0'
       gem 'activerecord', '< 5.1.5'
       gem 'aws-sdk'

Rakefile

@@ -59,6 +59,7 @@ namespace :spec do
   end
 
   [
+    :action_view,
     :active_model_serializers,
     :active_record,
     :active_support,
@@ -234,6 +235,10 @@ task :ci do
       sh 'bundle exec appraisal rails30-postgres rake spec:rails'
       sh 'bundle exec appraisal rails32-mysql2 rake spec:rails'
       sh 'bundle exec appraisal rails32-postgres rake spec:rails'
+      # Rails suite specs
+      sh 'bundle exec appraisal rails32-postgres rake spec:action_view'
+      sh 'bundle exec appraisal rails32-mysql2 rake spec:active_record'
+      sh 'bundle exec appraisal rails32-postgres rake spec:active_support'
     end
   elsif Gem::Version.new('2.1.0') <= Gem::Version.new(RUBY_VERSION) \
         && Gem::Version.new(RUBY_VERSION) < Gem::Version.new('2.2.0')
@@ -288,6 +293,10 @@ task :ci do
       sh 'bundle exec appraisal rails32-postgres rake spec:rails'
       sh 'bundle exec appraisal rails4-mysql2 rake spec:rails'
       sh 'bundle exec appraisal rails4-postgres rake spec:rails'
+      # Rails suite specs
+      sh 'bundle exec appraisal rails32-postgres rake spec:action_view'
+      sh 'bundle exec appraisal rails32-mysql2 rake spec:active_record'
+      sh 'bundle exec appraisal rails32-postgres rake spec:active_support'
     end
   elsif Gem::Version.new('2.2.0') <= Gem::Version.new(RUBY_VERSION)\
         && Gem::Version.new(RUBY_VERSION) < Gem::Version.new('2.3.0')
@@ -303,6 +312,7 @@ task :ci do
       sh 'bundle exec appraisal contrib rake test:sidekiq'
       sh 'bundle exec appraisal contrib rake test:sucker_punch'
       # Contrib specs
+      sh 'bundle exec appraisal contrib rake spec:action_view'
       sh 'bundle exec appraisal contrib rake spec:active_model_serializers'
       sh 'bundle exec appraisal contrib rake spec:active_record'
       sh 'bundle exec appraisal contrib rake spec:active_support'
@@ -370,6 +380,7 @@ task :ci do
       sh 'bundle exec appraisal contrib rake test:sidekiq'
       sh 'bundle exec appraisal contrib rake test:sucker_punch'
       # Contrib specs
+      sh 'bundle exec appraisal contrib rake spec:action_view'
       sh 'bundle exec appraisal contrib rake spec:active_model_serializers'
       sh 'bundle exec appraisal contrib rake spec:active_record'
       sh 'bundle exec appraisal contrib rake spec:active_support'
@@ -436,6 +447,7 @@ task :ci do
       sh 'bundle exec appraisal contrib rake test:sidekiq'
       sh 'bundle exec appraisal contrib rake test:sucker_punch'
       # Contrib specs
+      sh 'bundle exec appraisal contrib rake spec:action_view'
       sh 'bundle exec appraisal contrib rake spec:active_model_serializers'
       sh 'bundle exec appraisal contrib rake spec:active_record'
       sh 'bundle exec appraisal contrib rake spec:active_support'

docs/GettingStarted.md

@@ -26,6 +26,7 @@ To contribute, check out the [contribution guidelines][contribution docs] and [d
      - [Quickstart for OpenTracing](#quickstart-for-opentracing)
  - [Manual instrumentation](#manual-instrumentation)
  - [Integration instrumentation](#integration-instrumentation)
+     - [Action View](#action-view)
      - [Active Model Serializers](#active-model-serializers)
      - [Active Record](#active-record)
      - [Active Support](#active-support)
@@ -321,6 +322,7 @@ For a list of available integrations, and their configuration options, please re
 
 | Name                     | Key                        | Versions Supported       | How to configure                    | Gem source                                                                     |
 | ------------------------ | -------------------------- | ------------------------ | ----------------------------------- | ------------------------------------------------------------------------------ |
+| Action View              | `action_view`              | `>= 3.2, < 6.0`          | *[Link](#action-view)*              | *[Link](https://github.com/rails/rails/tree/master/actionview)*                |
 | Active Model Serializers | `active_model_serializers` | `>= 0.9`                 | *[Link](#active-model-serializers)* | *[Link](https://github.com/rails-api/active_model_serializers)*                |
 | Active Record            | `active_record`            | `>= 3.2, < 6.0`          | *[Link](#active-record)*            | *[Link](https://github.com/rails/rails/tree/master/activerecord)*              |
 | Active Support           | `active_support`           | `>= 3.2, < 6.0`          | *[Link](#active-support)*           | *[Link](https://github.com/rails/rails/tree/master/activesupport)*             |
@@ -345,11 +347,33 @@ For a list of available integrations, and their configuration options, please re
 | Resque                   | `resque`                   | `>= 1.0, < 2.0`          | *[Link](#resque)*                   | *[Link](https://github.com/resque/resque)*                                     |
 | Rest Client              | `rest-client`              | `>= 1.8`                 | *[Link](#rest-client)*              | *[Link](https://github.com/rest-client/rest-client)*                           |
 | Sequel                   | `sequel`                   | `>= 3.41`                | *[Link](#sequel)*                   | *[Link](https://github.com/jeremyevans/sequel)*                                |
-| Shoryuken                | `shoryuken`                | `>= 4.0.2`               | *[Link](#shoryuken)*                | *[Link](https://github.com/phstc/shoryuken)*
+| Shoryuken                | `shoryuken`                | `>= 4.0.2`               | *[Link](#shoryuken)*                | *[Link](https://github.com/phstc/shoryuken)*                                   |
 | Sidekiq                  | `sidekiq`                  | `>= 3.5.4`               | *[Link](#sidekiq)*                  | *[Link](https://github.com/mperham/sidekiq)*                                   |
 | Sinatra                  | `sinatra`                  | `>= 1.4.5`               | *[Link](#sinatra)*                  | *[Link](https://github.com/sinatra/sinatra)*                                   |
 | Sucker Punch             | `sucker_punch`             | `>= 2.0`                 | *[Link](#sucker-punch)*             | *[Link](https://github.com/brandonhilkert/sucker_punch)*                       |
 
+### Action View
+
+Most of the time, Active Support is set up as part of Rails, but it can be activated separately:
+
+```ruby
+require 'actionview'
+require 'ddtrace'
+
+Datadog.configure do |c|
+  c.use :action_view, options
+end
+```
+
+Where `options` is an optional `Hash` that accepts the following parameters:
+
+| Key | Description | Default |
+| ---| --- | --- |
+| `analytics_enabled` | Enable analytics for spans produced by this integration. `true` for on, `nil` to defer to global setting, `false` for off. | `false` |
+| `service_name` | Service name used for rendering instrumentation. | `action_view` |
+| `tracer` | `Datadog::Tracer` used to perform instrumentation. Usually you don't need to set this. | `Datadog.tracer` |
+| `template_base_path` | Used when the template name is parsed. If you don't store your templates in the `views/` folder, you may need to change this value | `'views/'` |
+
 ### Active Model Serializers
 
 The Active Model Serializers integration traces the `serialize` event for version 0.9+ and the `render` event for version 0.10+.
@@ -461,7 +485,7 @@ Where `options` is an optional `Hash` that accepts the following parameters:
 | Key | Description | Default |
 | ---| --- | --- |
 | `analytics_enabled` | Enable analytics for spans produced by this integration. `true` for on, `nil` to defer to global setting, `false` for off. | `false` |
-| `cache_service` | Service name used for caching with `active_support` instrumentation. | `'active_support-cache'` |
+| `cache_service` | Service name used for caching with `active_support` instrumentation. | `active_support-cache` |
 | `tracer` | `Datadog::Tracer` used to perform instrumentation. Usually you don't need to set this. | `Datadog.tracer` |
 
 ### AWS

lib/ddtrace.rb

@@ -21,6 +21,7 @@ module Datadog
   extend Contrib::Extensions
 end
 
+require 'ddtrace/contrib/action_view/integration'
 require 'ddtrace/contrib/active_model_serializers/integration'
 require 'ddtrace/contrib/active_record/integration'
 require 'ddtrace/contrib/active_support/integration'

lib/ddtrace/contrib/action_view/configuration/settings.rb

@@ -0,0 +1,24 @@
+require 'ddtrace/contrib/configuration/settings'
+require 'ddtrace/contrib/action_view/ext'
+
+module Datadog
+  module Contrib
+    module ActionView
+      module Configuration
+        # Custom settings for the ActionView integration
+        class Settings < Contrib::Configuration::Settings
+          option  :analytics_enabled,
+                  default: -> { env_to_bool(Ext::ENV_ANALYTICS_ENABLED, false) },
+                  lazy: true
+
+          option  :analytics_sample_rate,
+                  default: -> { env_to_float(Ext::ENV_ANALYTICS_SAMPLE_RATE, 1.0) },
+                  lazy: true
+
+          option :service_name, default: Ext::SERVICE_NAME
+          option :template_base_path, default: 'views/'
+        end
+      end
+    end
+  end
+end

lib/ddtrace/contrib/action_view/ext.rb

@@ -0,0 +1,17 @@
+module Datadog
+  module Contrib
+    module ActionView
+      # ActionView integration constants
+      module Ext
+        APP = 'action_view'.freeze
+        ENV_ANALYTICS_ENABLED = 'DD_ACTION_VIEW_ANALYTICS_ENABLED'.freeze
+        ENV_ANALYTICS_SAMPLE_RATE = 'DD_ACTION_VIEW_ANALYTICS_SAMPLE_RATE'.freeze
+        SERVICE_NAME = 'action_view'.freeze
+        SPAN_RENDER_PARTIAL = 'rails.render_partial'.freeze
+        SPAN_RENDER_TEMPLATE = 'rails.render_template'.freeze
+        TAG_LAYOUT = 'rails.layout'.freeze
+        TAG_TEMPLATE_NAME = 'rails.template_name'.freeze
+      end
+    end
+  end
+end

lib/ddtrace/contrib/action_view/instrumentation.rb

@@ -0,0 +1,192 @@
+require 'ddtrace/contrib/action_view/ext'
+
+module Datadog
+  module Contrib
+    module ActionView
+      # Defines instrumentation for ActionView
+      module Instrumentation
+        # Instrumentation for template rendering
+        module TemplateRenderer
+          # Rails < 3.1 template rendering
+          module Rails30
+            # rubocop:disable Metrics/MethodLength
+            def self.prepended(base)
+              # rubocop:disable Metrics/BlockLength
+              base.class_eval do
+                def render_with_datadog(*args, &block)
+                  # NOTE: This check exists purely for Rails 3.0 compatibility.
+                  #       The 'if' part can be removed when support for Rails 3.0 is removed.
+                  if active_datadog_span
+                    render_without_datadog(*args, &block)
+                  else
+                    datadog_tracer.trace(
+                      Ext::SPAN_RENDER_TEMPLATE,
+                      span_type: Datadog::Ext::HTTP::TEMPLATE
+                    ) do |span|
+                      with_datadog_span(span) { render_without_datadog(*args, &block) }
+                    end
+                  end
+                end
+
+                def render_template_with_datadog(*args)
+                  begin
+                    template = args[0]
+                    layout_name = args[1]
+
+                    # update the tracing context with computed values before the rendering
+                    template_name = template.try('identifier')
+                    template_name = Utils.normalize_template_name(template_name)
+
+                    if template_name
+                      active_datadog_span.set_tag(
+                        Ext::TAG_TEMPLATE_NAME,
+                        template_name
+                      )
+                    end
+
+                    if layout_name
+                      active_datadog_span.set_tag(
+                        Ext::TAG_LAYOUT,
+                        layout_name
+                      )
+                    end
+                  rescue StandardError => e
+                    Datadog::Tracer.log.debug(e.message)
+                  end
+
+                  # execute the original function anyway
+                  render_template_without_datadog(*args)
+                end
+
+                private
+
+                attr_accessor :active_datadog_span
+
+                def datadog_tracer
+                  Datadog.configuration[:action_view][:tracer]
+                end
+
+                def with_datadog_span(span)
+                  self.active_datadog_span = span
+                  yield
+                ensure
+                  self.active_datadog_span = nil
+                end
+
+                # method aliasing to patch the class
+                alias_method :render_without_datadog, :render
+                alias_method :render, :render_with_datadog
+
+                alias_method :render_template_without_datadog, :_render_template
+                alias_method :_render_template, :render_template_with_datadog
+              end
+            end
+          end
+
+          # Rails >= 3.1 template rendering
+          module Rails31Plus
+            def render(*args, &block)
+              datadog_tracer.trace(
+                Ext::SPAN_RENDER_TEMPLATE,
+                span_type: Datadog::Ext::HTTP::TEMPLATE
+              ) do |span|
+                with_datadog_span(span) { super(*args, &block) }
+              end
+            end
+
+            def render_template(*args)
+              begin
+                # arguments based on render_template signature (stable since Rails 3.2)
+                template = args[0]
+                layout_name = args[1]
+
+                # update the tracing context with computed values before the rendering
+                template_name = template.try('identifier')
+                template_name = Utils.normalize_template_name(template_name)
+                layout = layout_name.try(:[], 'virtual_path')
+
+                if template_name
+                  active_datadog_span.set_tag(
+                    Ext::TAG_TEMPLATE_NAME,
+                    template_name
+                  )
+                end
+
+                if layout
+                  active_datadog_span.set_tag(
+                    Ext::TAG_LAYOUT,
+                    layout
+                  )
+                end
+              rescue StandardError => e
+                Datadog::Tracer.log.debug(e.message)
+              end
+
+              # execute the original function anyway
+              super(*args)
+            end
+
+            private
+
+            attr_accessor :active_datadog_span
+
+            def datadog_tracer
+              Datadog.configuration[:action_view][:tracer]
+            end
+
+            def with_datadog_span(span)
+              self.active_datadog_span = span
+              yield
+            ensure
+              self.active_datadog_span = nil
+            end
+          end
+        end
+
+        # Instrumentation for partial rendering
+        module PartialRenderer
+          def render(*args, &block)
+            datadog_tracer.trace(
+              Ext::SPAN_RENDER_PARTIAL,
+              span_type: Datadog::Ext::HTTP::TEMPLATE
+            ) do |span|
+              with_datadog_span(span) { super(*args) }
+            end
+          end
+
+          def render_partial(*args)
+            begin
+              template_name = Utils.normalize_template_name(@template.try('identifier'))
+              if template_name
+                active_datadog_span.set_tag(
+                  Ext::TAG_TEMPLATE_NAME,
+                  template_name
+                )
+              end
+            rescue StandardError => e
+              Datadog::Tracer.log.debug(e.message)
+            end
+
+            # execute the original function anyway
+            super(*args)
+          end
+
+          private
+
+          attr_accessor :active_datadog_span
+
+          def datadog_tracer
+            Datadog.configuration[:action_view][:tracer]
+          end
+
+          def with_datadog_span(span)
+            self.active_datadog_span = span
+            yield
+          ensure
+            self.active_datadog_span = nil
+          end
+        end
+      end
+    end
+  end
+end